Document:Pinching reviews Adams

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Last week, Macmillans published a book, AIDS: The HIV Myth, which, the dust-cover announced, "challenges the claim that Aids is caused by a virus called HIV". Its author, journalist Jad Adams, propounds the view that human immunodeficiency virus, far from being the primary infectious agent that causes Aids, is nothing more than a "passenger virus" and that the causes of Aids lie elsewhere. Frankly, in my view, it is a disappointing book.

Mr. Adams does not present a coherent view of any alternatives. His arguments are so vague it is difficult to respond briefly to the many flaws; it is rather like fencing with blancmange. Some of his assumptions about the ground rules of human and retrovirus biology are manifestly incorrect.

He questions why not everyone with HIV has Aids. Most human pathogens cause serious disease only in a proportion of those infected, while in others they may go unnoticed. Witness the Hepatitis B virus. Furthermore, the incubation period for HIV and Aids has been estimated to be about seven years on average. Long incubation periods are not uncommon: tertiary syphilis, for example, may take even longer. If HIV-positive people are studied for 10 years, then about 50 percent develop Aids and 15 percent have other clinical disease. That, by any standards, is a high "attack rate" for a microorganism; many fear that, after longer periods of infection, it could be higher.

Mr. Adams says that many people with Aids show no evidence of HIV infection. But his claim is based on unrepresentative studies. In fact, evidence of HIV infection is found in virtually all patients with the clinical syndrome of Aids. Out of tens of thousands of cases, a handful have been reported of a disorder clinically indistinguishable from Aids but without the HIV virus being identified.

However, susceptibility to infection of the type seen in Aids can result from other causes. This is like clinical hepatits, which may result from viruses, alcohol or auto-immunity. Indeed, it is remarkable that such a heterogeneous clinical syndrome as Aids can so frequently be attributed to HIV infection. It remains to be seen whether the few discrepancies are due to the hitherto undetectable HIV or other causes.

Another concern Mr. Adams raises is the apparently low level of HIV detected in samples from Aids patients. However, a substantial body of evidence shows that HIV is, in fact, present to a considerable extent in body cells and tissues. There is an apparent paradox in that only one in 10,000 CD4 "helper" lymphocytes are found to be infected when viable blood cells in a patient with Aids or HIV are examined. But the paradox is false.

Aids largely results from the loss of CD4 lymphocytes; the cells are lost either because they have been damaged by the virus directly or, more likely, because the body's own immune mechanisms have eliminated the virus-infected cells. In this scenario, it is not surprising the remaining viable cells do not show a high frequency of infection. Try studying how bullets cause death in a battle. Of the soldiers still in action, few will have bullets in them. That, however, does not mean that bullets are not responsible for the killed and wounded.

Another false paradox in the book is the presence of antibodies to HIV in Aids patients. On Mr. Adams's simplistic reading of immunology, antibodies are supposed to protect against infection; so how is it that HIV, which causes a strong antibody response, can cause disease despite them? He gets very confused.

Although antibodies are made in response to any foreign material, including micro-organisms, they play a very limited role in defence against most viruses. Indeed, immune responses to HIV may, in fact, contribute substantially to the disease by eliminating HIV-infected CD4 lymphocytes. Also, in some circumstances, antibodies can enhance the production of virus by infected cells. The strong antibody response to HIV implies that the body sees plenty of HIV, even if laboratory tests show "low levels".

Mr. Adams says that retroviruses do not by their nature kill cells, but rather stimulate their growth, hence HIV cannot cause Aids. His argument is totally flawed. Retroviruses, including HIV, can damage cells directly or indirectly. An analogous argument would be that many bacteria are harmless; therefore, bacteria cannot cause disease. But some manifestly do.

Mr. Adams does not just move the goalposts, he moves the pitch and changes the rules. The book reads like a manifesto of the Flat Earth Society. It can only seem remotely plausible to the uninitiated by leaving out most relevant data or using data that is clearly wrong.

The book's position rests heavily on the advocacy of a few individuals, most of whom have little or no Aids research experience. Most important is Peter Duesberg, a senior and respected animal retrovirologist. Unfortunately his ideas betray an extraordinary lack of insight into the biology of Aids and a highly selective reading of the relevant scientific literature, regarding the evidence on HIV and Aids.

Another pervasive quality of this book is its belief in "conspiracy theory". The dust-jacket sets the tone: "a deliberate challenge to the complacency of the 'Aids establishment' – that group of scientists and politicians who have gained from claiming that Aids has a single, known cause".

The implication is that people who are perceived to have vested interests must always speak with forked tongue. Now, if you like that sort of thing then this is the book for you. It really lays it on with the shovel. But, if you are tempted to believe it, first examine the vast and well-validated scientific literature, which Mr. Adams conveniently ignores, before you draw your own conclusions.

I wonder what makes him think that clinicians caring for people with Aids could possibly "gain" from accepting the claim that HIV causes Aids if that claim really was false as he supposes? Worst of all, the book's tone is highly offensive to the many people who have to face Aids and HIV infection personally.

It is difficult to find any saving graces in this book. Its account is flawed and, almost always, accompanied by sideswipes at scientists. It does not marshall arguments, is strong on assertion and thin on data.

The hypothesis that HIV is the primary underlying cause of Aids is consistent with widely reproducible evidence; it has not yet been falsified, by this or any other supposed challenge. The alternatives proposed by Mr. Adams were not credible in 1983, and are even less so now.

As I see the evidence, HIV is no passenger, but a virus that has shown a devastating capacity for causing disease by well-defined mechanisms. I am prepared to keep an open mind, but can foresee no great likelihood that the basic hypothesis will be falsified. But then I imagine Mr. Adams would regard me as part of his mythical and supposedly monolithic "Aids establishment", so I would say that, wouldn't I? You, dear reader, are going to have to make up your own mind.

Anthony Pinching is Senior Lecturer in Clinical Immunology at St. Mary's Hospital Medical School, London